Will NYT release their sources?

US President Donald Trump reacted on The New York Times' Saturday report about Washington's cyber attack on Russian electric power grid in a warning to President Vladimir V. Putin and demanded NYT to disclose their sources.

The story in the @nytimes about the U.S. escalating attacks on Russia’s power grid is Fake News, and the Failing New York Times knows it. They should immediately release their sources which, if they exist at all, which I doubt, are phony. Times must be held fully accountable! Donald Trump.